Demand valve



United States Patent DEMAND VALVE Phillip E.: Meidenbauer, Jr.,.Bulfalo, N. Y assignor-.to Firewel Industries, Buffalo, N. Y., aco-partnership Application October 9, 1952, Serial No. 313,866

.8 :Claims. (Cl.2137-:64)

. This inventionzrelates-tozajdemand'valve suchasused in a mask tosupply oxygen or .air in response'to .the reducedpressure in the maskcaused by the inhalation of thewearer and which closes immediately.followingthe inhalation so that the air or oxygen is suppliedonly .asrequired. The use of the invention is not, however, confined to air oroxygen masks but may be used to'control the supply of any gas inresponse toademand for such gas as is evidencedby a reduced pressure onthe outlet side of the valve.

One of the principal .objects of the invention is to supply such ademandtvalve which is highly sensitive and is useful against .highpressures of air or oxygen and operated .by.relatively slight pressurevariations such as those caused by the; inhalation ofthe wearer of amask.

Another .object is to :.provide such a'demand .valve which isipartiallyselflenergizing sothat once openedit tends to keep itselfopen. lBy such characteristics a mask equipped Wlll'llthfi demand valveis less tiring since while a certain amount of inhalation energy isrequiredto open the demand valve,imuch less energy is requiredito holdthe demand valve open sothat little eifort is required by the wearer ofthe mask:for'the greater part of each inhalation.

Another object is .to provide 'such a demand valve which is very compactand can readily be installedrin the mask to control a high-pressure airor oxygen line leading to the mask. By carrying a high pressure linedirectlyto the. mask, it is unnecessary to use pressure reducing valves;a smaller and less' clumsy line a. can be brought tothe mask tofacilitate its application, removal and use; there is areducedpressuredropbetween the valve and thetdemandzone thereby to increase thesensitivity of the demand valve; and there is no dangerofcontaminationof the air oroxygen supplythrough' leakage since under highpressure theleakage would always be to the exterior to expelcontaminants.

Another object is to provide such a demand valve which can bexbranchedtoprovide. ahigh pressure air' or oxygen source forsome specialpurpose,'such as to supply a stream of dry airto preventxfogging ofthetgogglesof the mask or toaflow indicator.

Another object-is .to provide such a demand valve which is partiallyself-energizing on closing so as to avoid the necessity for aclosingspring or to permitof reducing the, strength ofsuchaspring. "Byeliminating or reducing the strength of such a" closing spring lessinhalation energy is required to'open the demand valve since openingofthe valve is notagainsta high spring loading.

Another objectoftheinvention is to provide such a demand. valvewhich issimple and reliable in construction and, operation soas to alwaysbeoperative without danger of leakage of the high pressure air oroxygen.

Another object is to provide such a demandvalve fu tllavea tie lcr ncest t rt bie and dxaataee tthe i v n ione ill h 2,821,990 Patented Feb. 4,1958 2 apparent '.-from the following description and drawings in:which:

-Fig. 1 -is.a fragmentary section .througha part of a mask equipped witha demand valveembodying the present invention.

.:-Fig. 2 is a similar view ofzthe .demand' valve on an enlarged scale.

Figs. 3, 4 and 5 are sectional views taken on the correspondinglynumbered lines on Fig. 2.

Fig.6 is a view, on.a reduced. scale, similar to Fig. 2 andshowingamodified form of the invention.

The demand valve. of the present invention is shown as used .inconjunction with supplyingair or oxygen from a relatively high pressuresupply line .10 to a mask: having atubular metal-shell 11 the interiorchamber 12 of which is in communication with the interior of the maskso'that a reduced pressure in the chamber 12 results on each inhalationofthe: wearer of the mask. By relatively high pressure .-oxygen;or1zairsupply is meant pressure in the order of from, say, 5103100 pounds gagepressure. The tubular.metal sh'ell 11 isshown as having a rim 13 ofreduced diamcteraovercwhich is fitted the rim 14 of a flexiblediaphragm. 15, suchas one made of rubber. The rim 14 of the diaphragm.can be held in contact with the reduced "rim-i13;'of.theitubular 'shell.11 by a cap 16, or many other suitablezmanner. This cap 16 is shown aspress fitted .over..the. rimzofthe rubber diaphragm and aslhaving'breatherzholes 17. The: rubber diaphragm is shown: as havingmarginal.annular corrugations 18 which tend :tobias itto the position shown,andiametal plate 19 is shown as secured centrally to. the side of thedia phragmfacing thechamber 12.

The tubular shell is shown as being formed to provide an angularlyprojecting cylindrical neck '20, the axis of which is directed generallytoward the. center of the diaphragm 15. This neck is bored to provideanoutwardly facing annular shoulder 21 and a short smooth bore 22 andbeyond this short smooth bore 22 is internally threaded, as indicated at23.

A metal-valve seat disk 25 is fitted in the shortsm-ooth bore "22against the annular shoulder 21,-this valve seat disk-having a centralopening 26. Preferably this opening 26 is of conical formenlarging andwithits-axis directed toward thecenter of the diaphragtnlS.

The side.of the valveseatdisk 25 opposite the chamber 12' is preferablyprovided with arubber facing or disk 28 and this rubber facing isprovided with an opening29 in registenwith the conical opening 26. .Therubber faced valve seat disk'25 is held in position: by ascrew plugorfollower 30 screwed intothe threads 23 and this screw plug havinganannular end bead31'bearing against the rubber facing 28 of the valveseat disk .25. .A'ring. seal 32 istpreferably interposed betweenthisbead.3.1.andrthe short smooth bore'22 to prevent leakage of'gas alongthe threads of the screw plug or follower 30. The high pressure inletline .10 preferably exten'dsv axiallythrough the screw plug vor follower30. The, high pressure air inlet line 10 is secured to extendthroughanddischarge into 1 the hollow interiorschamber: 34 of 'thescrew plug30.

The valyehead is in the .fornnof a cup 35 with an axially extendingrim36. seated on'the rubber'jfacing 28 of -the-valveseat disk 25. This-valve:hea'd. is alsosshown ashaving an'axial extension 38,projectingaway'gfrom the valve seat disk 25. In this axial extension 38 isanchored one end of a valve sternor rod 39 which projects- -through theopenings 29 and26 ofthe'rubber facing 28 and valve seat disk25,.respectively, and has a rounded end 40.arranged in closeproximity tothe center ofthe metal ,disk 19, mounted on the diaphragm 15.

..Fastqto thisrod, within the chamber'12, is arranged arbafifleor. vanemember 42.- This bafile'orvane member is shown as having a tubular neck43 press fitted around the rod 39 and also as having a circular conicalenlargement 44, the conical face 45 of which opposes the conical opening26 through the valve seat disk 25. The shape of the vane or bafilemember 42 is not of particular importance but its size and spacing fromthe valve seat disk 25 must be such that the expanding regular cone ofgas issuing from the conical opening 26 be of smaller cross sectionalsize than the enlarged part 44 of the vane at its point of impactagainst the vane and also that the cone of gas impinges against thiscircular enlarged part 44 with effective force.

In the form of the invention shown in Figs. 1-5, the demand valve isalso shown as having a return spring 46although such a return spring isnot essential. This spring biases the valve toward its closed positionand would only be essential if the effective force of the passing gasagainst the vane 42 were to exceed the effective force of this gasagainst the valve head 35. This spring is shown as being in the form ofa spiral compression spring with its large end bearing against the valveseat disk 25 and with its small end bearing against a small collar 48press fitted on the rod 39.

In the operation of the demand valve as above described, the highpressure of the gas supplied from the line to the chamber within thescrew plug 30 presses against the cup-shaped valve head 35 and holds itsrim 36 firmly against the rubber facing 28 of the valve seat disk 25.Accordingly this valve head 35 is held perpendicular to the valveseat'disk 35 and the valve stem or rod 39 is likewise held in a positionperpendicular to this valve seat disk. In this position the rounding end40 of this valve rod or stem is held in closely spaced relation to thecenter of the metal plate 19 on the diaphragm on the side of thisdiaphragm facing the demand chamber 12.

When the user of the mask inhales, the pressure in the mask is reducedand accordingly the pressure in this demand chamber 12 is reduced.Accordingly the diaphragm is moved to the left as viewed in Fig. l tocontact and move the free end 40 of the valve stem 39 laterally to theleft. This tips the cup-shaped valve head 35 laterally and henceseparates one side of the bead 36 of the valve head 35 from the rubberfacing 28 and permits the high pressuregas to escape through the valveopenings 29 and 26 into the demand chamber 12 in the form of anexpanding regular cone of gas.

In so flowing into the demand chamber 12 in the form of an expandingregular cone, the high pressure gas strikes the baffle or vane 42. Sincethis vane is now tipped with reference to the axis of the valve orifices29 and 26, and since the diameter of the enlarged part 44 of this vaneis greater than the cross sectional size of the expanding cone of thegas at the point of impact therewith, the flow of the gas tends to tipthis vane further and hence to drive the valve head 35 toward a furthertipped and further opened position. Thus, the impact of the gas fiowfrom the open valve is greater on the right hand side of the baffle orvane 42, as viewed in Fig. 2, than on the left hand side thereofandhence the kinetic force of the gas stream tends to tip the valve stem39 further to the left and to open the valve head 35 further. 'Ofcourse, this kinetic force of the gas stream against the vane or bafiie42 is not sufiicient to take control of the demand valve away from thedia phragm 15 but it reduces the force of this diaphragm required tohold the valve open. Since the force of the diaphragm 15 is a functionof the reduced pressure in the demand chamber 12, it is apparent that,once'the valve is opened, less negative pressure is required in thedemand chamber 12 to hold the valve open. Since this negative pressure,in an air or oxygen mask, is provided by the inhalation of the user, itwill be seen that while a certain inhalation effort is required to openthe demand valve, less inhalation effort is required to hold the valveopen and to complete the inhalation. Accordingly it will be seen thatthe vane or batfie 42 renders the demand valve partially self-energizingfollowing the initial opening to a degree which reduces the totalinhalation effort. By actual experience this inhalation effort isreduced a very substantial degree.

After the inhalation is complete, the pressure in the demand chamber 12rises, through the admission of high pressure gas past the demand valve,to the value of the pressure against the side of the diaphragm remotefrom the demand chamber. Accordingly this diaphragm, which is inherentlyso biased, moves to the right as viewed in Fig. l to its normalposition. This moves its metal plate 19 out of contact with the free endof the valve stem 39 and permits the valve parts to assume a closedposition.

The closing of the valve, when its parts are so released, is essentiallya function of the static pressure of the high pressure air in thechamber 34 against the convex side of the valve head 35. This staticpressure exceeds the kinetic force of the gas stream striking the vaneor bafile 42 and hence is effective in closing the valve. This closingforce can be augmented by the return spring 46, but this spring is notessential to the operation of the demand valve, as is illustrated in themodification, Fig. 6.

'In this modified form of the invention illustrated in Fig. 6, thedemand valve is again shown as used in conjunction with supplying air oroxygen to a mask having a tubular metal shell 11a the interior chamber12a of which is in communication with the interior of the mask so that areduced pressure in the chamber 12a results on each inhalation of thewearer of the mask. The showing of the diaphragm is not repeated in Fig.6 but the tubular shell 11a is again shown asbeing formed to provide anangularly projecting cylindrical neck 20a to which the gas is suppliedunder pressure in the same manner as with the form of the inventionshown in Figs. 1-5.

As with the form of the invention shown in Figs. l-S a metal valve seatdisk is provided with a coaxial conical through opening 51 the axis ofwhich is toward the center of the control diaphragm 15 (not shown). Thisvalve disk is, however, shown as press fitted from the demand chamber12a side against an annular shoulder or seat 52 in the bore or chamber53 to which the gas under pressure is supplied. On the side of the metalvalve seat disk 50 facing the bore 53 it is provided with a shallowcentral cylindrical recess 54 in which is fitted a secondary valve seatdisk 55. This secondary valve seat'disk has a rubber facing or disk 56which is held against a secondary annular shoulder or seat 58 in thebore or chamber 53.

This secondary valve seat disk and its rubber facing 56 have a throughopening 59 which registers with the through opening 51 of the main valveseat disk 50 and which is also in communication with a passage 60leading radially to the periphery of the main valve seat disk 50. -Inregister with this passage 60 the bore 53 can be provided with anannular groove 61 which connects, through a passage 62, with an outlettube or line 63. This tube 63 can lead to a flow indicator (not shown)or the gas flowing therethrough can be used for some other specialpurpose, such as to discharge against the goggles of the mask (also notshown) to prevent their fogging.

As with the form of the invention shown in Figs. l-5, the valve head isin the form of a cup 65 with an axially extending rim 66 seated on therubber facing 56 of the secondary valve seat disk 55. In the valve head65 is anchored a valve stem or rod 68 which projects through theopenings 59 and 51 and has its rounded head 69 arranged in closeproximity to the center of the metal disk 19 mounted on the diaphragm15.

I Fast to this rod, within the chamber 12a, is arranged a bafile or vanemember 70. This baffie or vane member 70 is shown'as having atubular'neck 71 press fitted around the rod 68. The efiective surface 72of the aim- .vane or. bafiieflm thati is, ,theface ppposingthe valveseat ,disks 50 and 55,;isgflat and .arrangedperperidicularly to thevalvesterner (rod 68in.contradistinction togthe conical face 45' of ,the form. .of,the invention shown, in Figs. 1-5..However,.jthe,diameterofthis vane. must be greater than thecro,ss..sectional-sizeQof theexpanding cone of gas at the point ofimpact therewith.

It will be seen 'thatthe operation ofthefformof the invention isessentiallythejs'ame as with the formof the inventiomshownin.Figs.,.1T5. 1Ihat is, when "the valve stem .68 is tipped to tipandnlnseatQthe valve head 65 on the rubber disk,56, theexpan'dingcone ofgas escaping past the open valve head '65 strikesjthebaflle or vane 70at such angle, due to the size of said vane and the tilt of this vane.or-baflie with the. valve stem, as to tend to hold the valveopen andthereby make the valve partially self-energizing in holding the valveopen. Similarly thevalve is partiallyself-energizing .on closing .due tothe static pressure.ofthe.gasbeingcontrolled againstithe valve head 65and which.tends to.-urge*this valve, head toward its closed position.{This pressure isgnormally suflicient to obviate the use of.a:valvereturn spring as with the spring 46 inthev form ,of-.,the,inventionshown in Figs. 1-5.

A particular distinguishing feature of the form of the invention shownin Fig. 6 is the conduit 60, 62 and 63 leading from the valve in advanceof the restriction or orifice formed by the small end of the conicalopening 51. Due to the pressure drop across this orifice, the airdelivered to this conduit is at a higher pressure than that whichobtains in the demand chamber 12a. Accordingly the high pressure air inthis conduit can be used to operate a flow indicator, to clear fog fromgoggles or for any other purpose where a stream of high pressure air,under control of the demand valve, is useful.

From the foregoing it will be seen that the present invention provides asimple, reliable and sensitive demand valve which requires less effortto open and close due to its partial self-energizing characteristics onboth opening and closing and which is also compact to permit of itsbeing incorporated directly in a mask. It will also be seen that thevalve can readily be designed to provide an auxiliary stream of highpressure air for any useful purpose.

I claim:

1. A demand valve of the character described for controlling the flow ofgas from a pressurized source, comprising a body having an orificesurrounded by an axially facing valve seat and from which orifice saidgas issues in the form of an expanding regular cone on the side of saidbody opposite said valve seat, a valve head engaging said valve seat andtiltable to permit gas to flow through said valve, a valve stem fast atone end to said valve head and projecting through said orifice in thedirection of said expanding cone of gas, means arranged to tilt saidvalve stem to tilt said valve head and open said valve, and a vane onsaid valve stem and arranged in the path of the gase escaping past theopen valve said vane being of larger cross sectional size than the crosssectional size of said expanding cone of gas at the point of impacttherebetween so that the impact of said escaping gas tends to maintainsaid valve stem in its tilted position.

2. A demand valve of the character described for controlling the flow ofgas from a pressurized source, comprising a body having an orificesurrounded by an axially facing valve seat and from which orifice saidgas issues in the form of an expanding regular cone on the side of saidbody opposite said valve seat, a valve head engaging said valve seat andtiltable to permit gas to flow through said valve, a valve stem fast atone end to said valve head and projecting through said orifice in thedirection of said expanding cone of gas, means arranged to tilt saidvalve stem to tilt said valve head and open said valve, and a roundbaffle member surrounding and fast to said valve stern and arranged inthe path of the gas escaping past the open valve said. vane being, oflarger cross sectional size thanthe crosssectionaltsize of saidexpandingcone of gas at the point of impacttherebetween so that; theimpact of. said escaping, gas tends to maintain said valve stem in itstilted position.

3. A demand valve of the character'described' forcontrollingthe flowofgas from a pressurized source, comprising a bodyhaving an orificesurrounded by an axially facing valve vseat and from which orificesaidgas issues in the form of an expanding regular .cone on the side ofsaid body opposite said valve seat, a rubber facing on said valve seat,a cup-shaped valve head having a rim engaging said rubber facing aroundsaid orifice. and tiltable to permit gas to flow through said valve, avalve stem fast at one end to said valvehead and projecting through saidorifice in the direction of said expanding cone of gas, means arrangedto tilt said valve stem to tilt said valve head and open said valve, anda vane fast to said valve stem and arranged in the pathof the expandingcone of gas escaping past the open valve said vane being of larger crosssectional size than the crosssectional size of said expanding cone ofgas at the point of impact therebetween so that the impact ofsaidescaping gas tends to maintain saidvalve stem inits. tiltedposition.

4. A demand valve of the character described'for controlling the flow ofgas from a pressurized source, comprising a body having a conical valveorifice enlarging toward the outlet side of the orifice and from whichorifice said gas issues in the form of an expanding regular cone, anaxially facing valve seat surrounding said orifice on the inlet side ofsaid orifice, means arranged to supply gas under pressure at the inletside of said orifice, a cupshaped valve head having a rim engaging saidvalve seat around said orifice and tiltable to permit gas to flowthrough said orifice, a valve stem fast at one end to said valve headand projecting through said orifice in the direction of said expandingcone of gas, means arranged at the outlet side of said orifice to tiltsaid valve stem to tilt said valve head and open said valve, and a vanefast to said valve stem on the outlet side of said orifice and arrangedin the path of the gas escaping through said orifice said vane being oflarger cross sectional size than the cross sectional size of saidexpanding cone of gas at the point of impact therebetween so that theimpact of said gas escaping through said orifice tends to maintain saidvalve stem in its tilted position.

5. A demand valve of the character described for controlling the flow ofgas from a pressurized source, comprising a body having an openingprovided with an annular seat, a valve seat disk fitting against saidseat, a rubber facing on the side of said valve seat disk opposite theside thereof engaging said annular seat, said valve seat disk and rubberfacing being provided with a central orifice extending therethrough andfrom which orifice said gas issues in the form of an expanding regularcone on the side of said body opposite said rubber facing, said orificethrough said valve seat disk being of conical form and enlarging awayfrom said rubber facing, means arranged to supply gas under pressurefrom said pressurized source against said rubber facing, a cup-shapedvalve head having a rim engaging said rub'ber facing around said orificeand tiltable to permit gas to flow through said orifice, a valve stemfast at one end to said valve head and projecting through said orificein the direction of said expanding cone of gas, means on the side ofsaid orifice opposite said rubber facing and arranged to tilt said valvehead and open said valve, and a vane fast to said valve stem andarranged in the path of the gas escaping through said orifice, said vanebeing of larger cross sectional size than the cross sectional size ofsaid expanding cone of gas at the point of impact therebetween so thatthe impact of said escaping gas tends to maintain said valve stem in itstilted position.

6. A demand valve of the character described, comprising a valve bodyhaving an opening, a pair of members arranged acrossandblocking said'ope'ning'and providing a space therebetween, an orifice through each ofsaid members and communicating, with said space, an axially facing valveseat on the side of'one of said members remote from said space, meansarranged to supply gas under pressure against said valve seat, a valvehead engaging said valve seat around the orifice therethrough andtiltable to permit a main stream of gas to escape through said orifices,and a conduit leading from saidspace to provide an auxiliary stream ofhigh pressure gas each time said valve is opened.

7. A demand valve as'set forth in claim 6 wherein said main stream ofgas issues from said orifices in the form of an expanding regular cone,wherein" a valve stem is fast at one end to said valve head and projectsthrough said orifices, wherein a van'e'is fast to'said valve stem on theside of said members'remote from said valve seat and is arranged in thepath of said expanding cone of gas, said vane being of larger crosssectional size than the cross sectional size of said expanding cone ofgas at the point of impact therebetween so that the impact of the gasescaping through said orifices tends to maintain said valve stem in itstilted position. I

8. A demand valve as set forth in claim 6 wherein said main streamof'gas issues from said orifices in the form of an expanding regularcone, wherein a valve stem is fast at one end to'said valve head andprojects through said orifices, wherein said members are in the form ofdisks, wherein said valve seat is in the form of a rubber facing on thecorresponding disk, and wherein a vane is fast to said valve stem on theside of said disks remote from said rubber facing and is arranged in thepath of said expanding cone of gas, said vane being of larger crosssectional size than the cross sectional size of said expanding cone ofgas at the point of impact 'therebetween so that the impact of the gasescaping through said orifices tends to maintain said valve stem in itstilted position.

References Cited inthe file of this patent UNITED STATES PATENTS1,066,178 Bonnell July 1, 1913 1,231,822 Warman July 3, 1917 1,789,964Buehrer Jan. 27, 1931 2,295,208 Grove Sept. 8, 1942 2,406,888Meidenbauer Sept. 3, 1946 2,445,359 Meidenbauer July 20, 1948

